The Transformers director caused a furore among fans of the long-running series last year when he told an interviewer that the famous "heroes in a half-shell" would be extra-terrestrials in a forthcoming Bay-produced reboot, which is being directed by Jonathan Liebesman. However, in a new interview with Movieline, the film-maker makes it clear that he is now sticking with the traditional origins story for Leonardo, Donatello, Raphael and Michelangelo.

"There was that quote saying that we're making [the Ninja Turtles as] aliens. We're not. It's the ooze! It's from the original source material. These are from the original writers, and I never went out to correct myself in the press," Bay said. "I do listen to the fans and I do want this to be authentic. I think they're going to be really happy with this movie. When I see the digital stuff, the turtles look great."

The news will come as some solace to fans, who took to Twitter and Facebook last year to criticise plans to change the turtles' backstory. In the original comic books, TV series and films, the heroes are mutants who gain anthropomorphic powers after encountering radioactive ooze. However Bay said in March last year that they would be "from an alien race" as well as "tough, edgy, funny, and completely lovable", sparking a backlash from Turtle aficionados.

The director then compounded the issue by issuing an irritable statement calling for fans to "take a breath, and chill", and pointing out that they had "not read the script". He added: "Our team is working closely with one of the original creators of Ninja Turtles to help expand and give a more complex backstory. Relax, we are including everything that made you become fans in the first place. We are just building a richer world."

Due in cinemas for June 2014, Teenage Mutant Ninja Turtles also appears to have regained its full title after at one point being billed as simply "Ninja Turtles". The film will star Transformers' Megan Fox as Turtle sidekick April O'Neil alongside Will Arnett, Danny Woodburn, Alan Ritchson, Noel Fisher, Jeremy Howard and Pete Ploszek.